CN102214256A - Method for extracting characteristic parameters of automotive crash waveform and establishing trapezoidal wave - Google Patents

Abstract

The invention discloses a method for extracting characteristic parameters of automotive crash waveform and establishing trapezoidal wave, relating to the technical field of automotive crash safety, wherein the method comprises acquiring automotive body acceleration information data from a data acquisition system in an automotive crash test to obtain an acceleration A(t); identifying the wave peak points and wave trough points in the acceleration A(t); and establishing a waveform function f(t) with a double-trapezoidal wave characteristic according to the acceleration A(t), a similarity principle and a principle of momentum conservation. In the invention, a mathematical model simplifying a complex and diversified crash acceleration waveform to be equivalent to a double-trapezoidal wave formulation is formed, and has an application value of simplifying a complex problem and an engineering value of solving the equivalent relationship between action time and energy of a double-trapezoidal wave by applying a principle of momentum conservation and a similarity principle; the model has a repeatability in an engineering and expands the popularization and practical application of the double-trapezoidal wave parameters, and can be realized by a specific method on a computer.

Description

A kind of car crass waveform character parameter extraction and trapezoidal wave construction method

Technical field

The present invention relates to the automotive crash safety technical field, particularly a kind of crash data treatment technology, specifically a kind of by the data processing method that equivalence becomes double-trapezoidal wave is simplified in the identification of collision acceleration wave shape.

Background technology

In the automotive crash safety technology, vehicle body acceleration is by being installed in the series data that acceleration transducer on the vehicle body forms after to the collision process acquisition and recording by the data acquisition system (DAS) of vehicle impact testing, be the significant data in the vehicle safety structural design, the automotive crash safety Journal of Sex Research is had directive significance.By analysis to collision acceleration wave shape, can find the problem that crashworthiness exists in the design process, and automobile product design be made the judgement that improves design in conjunction with collision theory, become the foundation that body structure is optimized design.

Simplify for the analysis significance of collision process the vehicle body acceleration waveform great, double-trapezoidal wave is to be subjected to the notion that industry is paid close attention in recent years, it is reduced to the automobile collision procedure of complexity the double-trapezoidal wave of equivalence, usually it has been carried out qualitative description in the prior art, and be not being described of how obtaining concrete waveform parameter.Obtaining often of double-trapezoidal wave parameter carried out subjective judgement by the technician according to practical engineering experience, and this judgement often has very big randomness, be difficult to lot of data is carried out statistical induction, how characteristic parameter for double-trapezoidal wave fails to make specific descriptions with the corresponding relation of actual collision acceleration, and the concrete parameter of how going to find the solution in the double-trapezoidal wave does not provide concrete computing method, therefore, the dependence experience estimates to calculate the double-trapezoidal wave parameter needs very high technical merit and the accumulation of actual engineering, limited popularizing and practical application of double-trapezoidal wave parameter, and be difficult to realize with concrete method on computers.

Summary of the invention

In order to enlarge popularizing and practical application of double-trapezoidal wave parameter, can realize with concrete method on computers, the invention provides a kind of car crass waveform character parameter extraction and trapezoidal wave construction method, see for details hereinafter and describe:

(1) from the data acquisition system (DAS) of vehicle impact testing, gathers the vehicle body acceleration information data, obtain acceleration A (t);

(2) discern wave crest point, trough point in the described acceleration A (t);

(3), make up wave function f (t) with double-trapezoidal wave feature according to similarity principle and principle of conservation of momentum according to described acceleration A (t); Wherein,

The horizontal ordinate of the wave function f (t) of described double-trapezoidal wave feature is the time variable axle, ordinate is described acceleration A (t) variable axle, the wave function f (t) of described double-trapezoidal wave feature is made of A, B, C, D, E and 6 data points of F, and corresponding coordinate figure is respectively (t ₀, G ₀), (t ₁, G ₁), (t ₂, G ₁), (t ₃, G ₂), (t ₄, G ₃) and (t ₅, G ₀); Wherein, A (t ₀, G ₀) be the double-trapezoidal wave starting point, t ₀Be the collision initial moment of contact, and t ₀=0; F (t ₅, G ₀) be the double-trapezoidal wave terminating point, t ₅For colliding the finish time; G ₀Actual value be 0; The coordinate figure of described A, B, C, D, E and F6 data point formation is respectively (0,0), (t ₁, G ₁), (t ₂, G ₁), (t ₃, G ₂), (t ₄, G ₃) and (t ₅, 0); Or,

The wave function f (t) of described double-trapezoidal wave feature is made up of AB, BC, CD, DE and five line segments of EF, and line segment BC and DE correspond respectively to G for being parallel to described time variable axle ₁And G ₂, line segment AB, CD and EF are the stringcourse of double-trapezoidal wave, respectively corresponding line segment function f _AB(t), f _CD(t) and F _EF(t); Wherein,

f _AB(t)＝K _AB×t；

f _CD(t)＝K _CD×t+b _CD；

f _EF(t)＝K _EF×t+b _E；；

K _AB, K _CDAnd K _EFBe described line segment function f _AB(t), f _CD(t) and f _EF(t) slope, b _CDAnd b _EFBe described line segment function f _CD(t) and f _EF(t) intercept;

Wherein, wave crest point, the trough point in the described acceleration A of identification (t) is specially described in the step (2):

The mean value of described wave crest point both sides at certain time intervals is all less than crest value; The mean value of described trough point both sides at certain time intervals is all greater than the trough value; (t) carries out the search of described wave crest point and described trough point to described acceleration A, and the number of times of search is N, and the value of N is a positive integer; Definition maximum valley peak A PVmax and maximum peak valley AVPmax, the search sequence of paddy peak value number are i, and the search sequence of peak-to-valley value number is j;

Wherein, according to described acceleration A (t), make up wave function f (t) according to similarity principle and principle of conservation of momentum and be specially described in the step (3) with double-trapezoidal wave feature:

According to first wave crest point P that occurs in the described acceleration A (t) ₁And the line segment between the described starting point A makes up described line segment function f _AB(t);

At described first wave crest point P ₁The peak valley point and the peak point P of the maximum valley peak value correspondence of Chu Xianing afterwards _I+1Make up described line segment function f _CD(t);

According to

Obtain the value of i;

Peak point P according to maximum peak valley correspondence _jMake up described line segment function f with the F point _{EF (t)}

According to

Obtain the value of j;

Definition temporary variable t ₁', t ₂' and G ₁' replacement t ₁, t ₂, G ₁B ' and C ' replace B and C, because f _AB(t)=f _CD(t)=G ₁', then have

${{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}=\frac{K_{\mathrm{CD}}\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}+b_{\mathrm{CD}}}{K_{\mathrm{AB}}}$

G ₁′＝K _CD×t ₂′+b _CD

By AB ' C ' t ₂' constituted one trapezoidal, its trapezoidal area

${\mathrm{<figure-callout\; id="1"\; label="S\; f"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_f=\frac{(2\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}-{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;})\&times;{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}^{\&prime;}}{2}=\frac{K_{\mathrm{CD}}\&times;(2\&times;K_{\mathrm{AB}}-K_{\mathrm{CD}})\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;2}+2\&times;K_{\mathrm{AB}}\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}+{{\mathrm{<figure-callout\; id="2"\; label="b\; CD"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">b</figure-callout>}}_{\mathrm{CD}}}^2}{2\&times;K_{\mathrm{AB}}};$

The area of A in the identical time period (t) is

Area according to A (t) in the identical time period and f (t) is equal, then S _A1=S _F1

${\&Integral;}_0^{{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}}A\left(t\right)\mathrm{dt}=\frac{K_{\mathrm{CD}}\&times;(2\&times;K_{\mathrm{AB}}-K_{\mathrm{CD}})\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;2}+2\&times;K_{\mathrm{AB}}\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}+{{\mathrm{<figure-callout\; id="2"\; label="b\; CD"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">b</figure-callout>}}_{\mathrm{CD}}}^2}{2\&times;K_{\mathrm{AB}}}$

By continuous adjustment t ₂' t when iterative computation finds area to equate ₂', its Rule of judgment is t ₂=t ₂' | _DS=0Wherein, dS=S _A1-S _F1

At segment [t ₃, t ₅], the area of A (t) is S _A2,

Polygon t ₂CDEt ₅The area that constitutes is by t ₂CDt ₃Trapezoidal, t ₃DEt ₄Rectangle and t ₄Et ₅Triangle is formed,

${\mathrm{<figure-callout\; id="2"\; label="S\; f"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">S</figure-callout>}}_f=\frac{({\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1+G_2)\&times;(t_3-t_2)}{2}+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_4-t_3)+\frac{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_5-t_4)}{2}$

Area according to A (t) in the identical time period and f (t) is equal, then S _A2=S _F2

$\left\{\begin{array}{c}{\&Integral;}_{t_2}^{t_5}A\left(t\right)\mathrm{dt}=\frac{({\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1+G_2)\&times;(t_3-t_2)}{2}+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_4-t_3)+\frac{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_5-t_4)}{2}\\ {\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=K_{\mathrm{CD}}{\&times;t}_3+{\mathrm{<figure-callout\; id="2"\; label="b\; CD\; G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">b</figure-callout>}}_{\mathrm{CD}}& \\ G_{}{}_2=K_{\mathrm{EF}}\&times;t_4+b_{\mathrm{EF}}\end{array}\right.$

${\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=\frac{-{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">H</figure-callout>}}_2+\sqrt{{{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">H</figure-callout>}}_2}^2-4{\&times;\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1\&times;H_3}}{2{\&times;\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1};$ $t_3=\frac{G_2-b_{\mathrm{CD}}}{K_{\mathrm{CD}}};$ $t_4=\frac{G_2-b_{\mathrm{EF}}}{K_{\mathrm{EF}}};$

Wherein, ${\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1=\frac{1}{K_{\mathrm{EF}}}-\frac{1}{K_{\mathrm{CD}}};$ ${\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">H</figure-callout>}}_2=\frac{G_1-b_{\mathrm{CD}}}{K_{\mathrm{CD}}}-\frac{b_{\mathrm{EF}}}{K_{\mathrm{EF}}}+t_5-{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2;$ $H_3={\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1\&times;t_2-\frac{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1\&times;b_{\mathrm{CD}}}{K_{\mathrm{CD}}}-2\&times;{\mathrm{<figure-callout\; id="2"\; label="S\; a"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">S</figure-callout>}}_a.$

The beneficial effect of technical scheme provided by the invention is:

The invention provides a kind of car crass waveform character parameter extraction and trapezoidal wave construction method, the present invention has formed a crash acceleration waveform complicated and changeable has been simplified the mathematical model of equivalence for the double-trapezoidal wave statement, its using value is a challenge is oversimplified, with 10 ³The crash acceleration series data of the order of magnitude is reduced to 6 series datas; Its construction value is to use principle of conservation of momentum and similarity principle has solved the equivalent relation of double-trapezoidal wave on action time and energy, this double-trapezoidal wave is equivalent with actual waveform on macroscopical waveform, the method of Xing Chenging has repeatability on engineering thus, enlarged popularizing and practical application of double-trapezoidal wave parameter, can realize with concrete method on computers.

Description of drawings

Fig. 1 is the process flow diagram of a kind of car crass waveform character parameter extraction provided by the invention and trapezoidal wave construction method;

Fig. 2 is the synoptic diagram of typical collision process acceleration waveform provided by the invention;

Fig. 3 is that Wave crest and wave trough provided by the invention calculates principle schematic;

Fig. 4 is the synoptic diagram of peak-to-valley value provided by the invention and paddy peak value;

Fig. 5 is the synoptic diagram of equivalent double-trapezoidal wave provided by the invention;

Fig. 6 is the synoptic diagram of fundamental function provided by the invention;

Fig. 7 finds the solution synoptic diagram for B point provided by the invention and C point;

Fig. 8 finds the solution synoptic diagram for D point provided by the invention and E point;

Fig. 9 resolves process flow diagram for double-trapezoidal wave provided by the invention;

Figure 10 is a car crass vehicle body acceleration channel data file layout synoptic diagram provided by the invention;

Figure 11 is a car crass vehicle body acceleration oscillogram provided by the invention;

Figure 12 is an acceleration waveform medium wave peak trough point synoptic diagram provided by the invention;

Figure 13 finds the solution F point synoptic diagram for speed Speed provided by the invention (t);

Figure 14 is the synoptic diagram of finding the solution of fundamental function provided by the invention;

Figure 15 finds the solution example schematic for B point provided by the invention and C point;

Figure 16 finds the solution example schematic for D point provided by the invention and E point;

Figure 17 is the synoptic diagram of acceleration waveform A provided by the invention (t) and equivalent double-trapezoidal wave f (t).

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, embodiment of the present invention is described further in detail below in conjunction with accompanying drawing.

In order to enlarge popularizing and practical application of double-trapezoidal wave parameter, can realize that the embodiment of the invention provides a kind of car crass waveform character parameter extraction and trapezoidal wave construction method with concrete method on computers, see for details hereinafter and describe:

A kind of car crass waveform character parameter extraction and trapezoidal wave construction method, this method is used for simplifying equivalent automobile collision procedure acceleration waveform, the so-called simplification is meant that the contour shape that characterizes the crash acceleration waveform with double-trapezoidal wave, so-called equivalence are meant that this double-trapezoidal wave and crash acceleration waveform have same effect on energy.

101: from the data acquisition system (DAS) of vehicle impact testing, gather the vehicle body acceleration information data, obtain acceleration A (t);

Wherein, referring to Fig. 1, the information data of acceleration A (t) is the acceleration information series that changes along with the time, and acceleration A (t) and time relationship are waveform.

102: wave crest point, trough point in the identification acceleration A (t);

Referring to Fig. 2, the zero timetable of A (t) is shown the zero hour that bumps, and A (t) waveform undulate attitude promptly has crest that trough is also arranged, and after crest is arranged earlier trough arranged, and the number of crest and trough equates.The common feature of wave crest point and trough point is that the derivative to the time is zero, and difference is that the mean value of wave crest point both sides at certain time intervals is all less than this crest value; The mean value of trough point both sides at certain time intervals is all greater than this trough value, and the embodiment of the invention will be distinguished the method for discerning as wave crest point and trough point.Use P _iThe set of variables of crest value is deposited in expression, uses V _jThe set of variables of trough value is deposited in expression, and i and j represent the sequence number of crest and trough respectively, and the value of i and j is the positive integer more than or equal to 1.With time t is independent variable, in calculating, defined a time interval variable Δ t especially, remove the little Wave crest and wave trough point that may occur among the A (t) by time interval variable Δ t, the big I of time interval variable Δ t carries out deciding according to practical situations, during specific implementation, the embodiment of the invention does not limit this.The time domain scope of independent variable t is [t ₀+ Δ t～t _N-Δ t], t ₀Be the zero-time among the A (t), t _NBe the concluding time among the A (t), defining variable t ', the span of t ' is [t ₀+ Δ t, t _N-Δ t].

A (t) is done differential calculation, obtain A ' (t);

$A^{\&prime;}\left(t\right)=\mathrm{dA}\left(t\right)/\mathrm{dt}|\begin{array}{c}t=t^{\&prime;}+\mathrm{\&Delta;t}\\ t=t^{\&prime;}-\mathrm{\&Delta;t}\end{array}---\left(1\right)$

Obtain the mean value A of t ' in the Δ t time period of front and back _{Ave+ Δ t}And A _{Ave-Δ t}

Wherein, A _{Ave+ Δ t}Be expressed as the mean value of t ' in the Δ t time period afterwards; A _{Ave-Δ t}Be expressed as the mean value of t ' in the Δ t time period before.

This step is specially: suppose current independent variable t=t ', and A ' (t)=0, obtain A according to second formula and the 3rd formula _{Ave+ Δ t}And A _{Ave-Δ t}

$A_{\mathrm{ave}+\mathrm{\&Delta;t}}=\mathrm{ave}\left\{A\left(t\right)\right\}|\begin{array}{c}t=t^{\&prime;}+\mathrm{\&Delta;t}\\ t=t^{\&prime;}\end{array}---\left(2\right)$

$A_{\mathrm{ave}-\mathrm{\&Delta;t}}=\mathrm{ave}\left\{A\left(t\right)\right\}|\begin{array}{c}t=t^{\&prime;}\\ t=t^{\&prime;}-\mathrm{\&Delta;t}\end{array}---\left(3\right)$

At [t ₀+ Δ t～t _N-Δ t] in the time period, if A ' (t)=0, two kinds of possibilities are then arranged, promptly be wave crest point or be the trough point, need be distinguished this moment by second formula and the 3rd formula, suppose that current point in time is t ', and the vehicle body acceleration figure of correspondence is A (t '), current crest sequential value is i, and wave crest point and trough point are used the 4th formula and the 5th formulate respectively:

P _i(t’，A(t’))|dA’(t’)＝0；A(t’)＞A _ave+Δt；A(t’)＞A _ave-Δt (4)

V _j(t’，A(t’))|dA’(t’)＝0；A(t’)＜A _ave+Δt；A(t’)＜A _ave-Δt (5)

Referring to Fig. 3, for the vehicle body acceleration waveform that presents wave characteristics, crest and trough are to occur in pairs, can think that thus crest and trough have constituted one group of peak valley sequence, on time relationship crest preceding, trough after.P _i, P _I+1And V _jCorresponding respectively coordinate figure is [tp _i, A (tp _i)], [tp _I+1, A (tp _I+1)] and [tv _j, A (tv _j)], suppose with the trough to be reference, the agreement peak-to-valley value is A _PV(i), the paddy peak value is A _VP(j), obtain A according to the 6th formula and the 7th formula _PV(i) and A _VP(j):

A _PV(i)＝A(tp _i)-A(tv _j) (6)

A _VP(j)＝A(tp _i+1)-A(tv _j)(7)

A (t) is carried out the search of wave crest point and trough point, the search sequence of the search sequence of definition maximum valley peak value, maximum peak valley, paddy peak value number and peak-to-valley value number;

Wherein, the number of times that A (t) is carried out the search of wave crest point and trough point is N, and the value of N is a positive integer; The maximum valley peak value is defined as APVmax, and the maximum peak valley is defined as AVPmax, and i is the search sequence number of paddy peak value, and j is the search sequence number of peak-to-valley value.

103:, make up wave function f (t) with double-trapezoidal wave feature according to similarity principle and principle of conservation of momentum according to acceleration A (t).

The purpose of the embodiment of the invention is the method that how extracts the parameter value that constitutes f (t) feature from vehicle body acceleration A (t), promptly calculates and can reflect f (t) actual value (t ₁, t ₂, t ₃, t ₄, t ₅, G ₁, G ₂).According to similarity principle, from the feature of the Wave crest and wave trough of A (t), make up the grown form of f (t), calculate the f (t) that equates with A (t) area according to principle of conservation of momentum then, promptly double-trapezoidal wave and actual collision acceleration waveform can correspond to two ascending waves and an end ripple, f _AB(t), f _CD(t) and f _EF(t) determined the grown form of double-trapezoidal wave f (t), [t ₀, t ₅] having determined the border of f (t), the embodiment of the invention is at first to obtain to constitute f (t) boundary value from A (t) for this reason, promptly solves border A point and F point, the i.e. t of double-trapezoidal wave ₀, t ₅And y ₀Actual value.Then A (t) is carried out wave crest point and the calculating of trough point, and in wave crest point and trough point, choose the constraint function f that formation constraint BCDE is ordered _AB(t), f _CD(t) and f _EF(t), at first calculate the BC point on the basis of constraint condition having, calculate the DE point then.Finally constituted double-trapezoidal wave f (t) by ABCDEF6 point.Wherein, A (t) has identical physical significance with the independent variable of f (t), can become the relation of mutual mapping.

Referring to Fig. 4, make up a wave function f (t) according to similarity principle with double-trapezoidal wave feature, set up A (t) the data characteristics relation function relevant by waveform character identification with f (t) to A (t), according to principle of conservation of momentum in the collision process, obtain by iterative computation and can reflect and A (t) process equivalence and parameter value that can quantitatively characterizing f (t) on momentum.

The horizontal ordinate of the wave function f (t) of the double-trapezoidal wave feature in the embodiment of the invention is the time variable axle, and ordinate is an acceleration variable axle, and f (t) is made of A, B, C, D, E and 6 data points of F, and corresponding coordinate figure is respectively (t ₀, G ₀), (t ₁, G ₁), (t ₂, G ₁), (t ₃, G ₂), (t ₄, G ₃) and (t ₅, G ₀).Wherein, A (t ₀, G ₀) be the double-trapezoidal wave starting point, t ₀Be defined as the collision initial moment of contact (zero constantly), and t ₀=0.F (t ₅, G ₀) be the double-trapezoidal wave terminating point, t ₅For colliding the finish time, G ₀Actual value be 0, i.e. G ₀=0.Specifically, the coordinate figure of A, B, C, D, E and F6 data point formation is respectively (0,0), (t ₁, G ₁), (t ₂, G ₁), (t ₃, G ₂), (t ₄, G ₃) and (t ₅, 0).

F (t) also can be regarded as by AB, BC, CD, DE and five line segments of EF and forms, and line segment BC and DE correspond respectively to G for being parallel to the time variable axle ₁And G ₂, line segment AB, CD and EF are the stringcourse of double-trapezoidal wave, respectively corresponding line segment function f _AB(t), f _CD(t) and f _EF(t), get access to the line segment function f according to the 8th formula, the 9th formula and the tenth formula _AB(t), f _CD(t) and f _EF(t):

f _AB(t)＝K _AB×t (8)

f _CD(t)＝K _CD×t+b _CD (9)

f _EF(t)＝K _EF×t+b _EF (10)

K in the formula _AB, K _CDAnd K _EFBe the line segment function f _AB(t), f _CD(t) and f _EF(t) slope, b _CDAnd b _EFBe the line segment function f _CD(t) and f _EF(t) intercept with the numerical relation of coordinate figure is:

K _AB＝G _1/t ₁；K _CD＝(G ₂-G _1)/(t ₃-t ₂₎；b _CD＝G ₁-K _CD×t ₂；K _FF＝G _2/(t ₅-t ₄₎；b _EF＝G ₂-K _FF×t ₄。

F (t) is at interval [t ₀-t _C] in can be represented by the formula

$f\left(t\right)=\left\{\begin{array}{cc}0& t=0;t=t_5\\ f_{\mathrm{AB}}\left(t\right)& {\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA0000062765050000012.png,HDA0000062765050000021.png"\; state="\{\{state\}\}">t</figure-callout>}}_0>t{\&GreaterEqual;t}_1\\ G_1& {\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1>t{\&GreaterEqual;t}_2\\ f_{\mathrm{CD}}\left(t\right)& {\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2>t\&GreaterEqual;t_3\\ G_2& t_3>t{\&GreaterEqual;t}_4\\ f_{\mathrm{EF}}\left(t\right)& t_4>t{>t}_5\end{array}\right.---\left(11\right)$

Definition initial collision characteristic area A1 is by A, B, C and t ₂Form, the definition second collision characteristic area A2 is by t ₂, C, D, E and F form.

According to the double-trapezoidal wave feature as can be known, frontier point A is the starting point of double-trapezoidal wave, and the F point is an end point.Can reflect that an A and the eigenwert of some F are t ₀, t ₅A can be considered to t as the initial point of collision ₀=0, G ₀=0.Need definite t that has only ₅, t ₅It is the finish time that is defined as colliding, according to kinematic principle as can be known, it between speed and the acceleration integral relation, promptly A (t) is carried out integral and calculating and try to achieve corresponding velocity function Speed (t), suppose that actual collision speed Velocity is a known quantity, the time point that Velocity equates or is similar to then at first occurs, be t ₅, its expression formula is as follows:

Speed(t)＝∫A(t)dt (12)

${\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="HDA0000062765050000061.png,HDA0000062765050000071.png"\; state="\{\{state\}\}">t</figure-callout>}}_5=\underset{0\&le;t\&le;t\max }{\mathrm{<figure-callout\; id="0"\; label="min"\; filenames="HDA0000062765050000012.png,HDA0000062765050000021.png"\; state="\{\{state\}\}">min</figure-callout>}}|\mathrm{speed}\left(t\right)-\mathrm{Velocity}|---\left(13\right)$

According to first wave crest point P that occurs among the A (t) ₁And the line segment between the initial point A makes up the line segment function f _AB(t);

At first wave crest point P ₁The peak valley point of the maximum valley peak value correspondence of Chu Xianing is V afterwards _iWith peak point P _I+1Make up the line segment function f _CD(t);

According to

Obtain the value of i;

Peak point P according to maximum peak valley correspondence _jMake up the line segment function f with the F point _EF(t);

According to Obtain the value of j.

Made up the line segment function f by above-mentioned steps _AB(t) required data point [0,0] and [tp ₁, A (tp ₁)]; Make up the line segment function f _CD(t) required data point [tp _I+1, A (tp _I+1)] and [tv _i, A (tv _i)]; Make up the line segment function f _EF(t) required data point [tp _j, A (tp _j)] and [t ₅, 0], wherein,

f _AB(t)＝K _AB×t

f _CD(t)＝K _CD×t+b _CD

f _EF(t)＝K _EF×t+b _EF

G ₀＝0；t ₀＝0

K _AB＝A(tp ₁)/tp ₁

K _CD＝(A(tp _i+1)-tv _i)/(tp _i+1-tv _i)

K _EF＝-A(tp _j)/(t ₅-tp _j)

b _CD＝A(tv _i)-K _CD×tv _i

b _EF＝A(tp _j)-K _EF×tp _j

Referring to Fig. 5, by the line segment function f _AB(t), f _CD(t) and f _EF(t) build the basic configuration of double-trapezoidal wave, waited to ask parameter G among the figure ₁In the line segment function f _AB(t) and f _CD(t) region S 1 that surrounds between changes, and waits to ask parameter G ₂At f _CD(t) and f _EF(t) region S 2 that surrounds between changes, and the B point is subjected to f _AB(t) and G ₁The region of variation constraint has formed parametric t to be asked ₁Region of variation, the C point is subjected to f _CD(t) and G ₁The region of variation constraint has formed parametric t to be asked ₂Region of variation, the D point is subjected to f _CD(t) and G ₂The region of variation constraint has formed parametric t to be asked ₂Region of variation, the E point is subjected to f _EF(t) and G ₂The region of variation constraint has formed parametric t to be asked ₄Region of variation can be found out thus because f _AB(t), f _CD(t), f _EF(t) structure has played restriction to unique point BCDE among the double-trapezoidal wave f (t), and scope has separately been arranged, for next step finds the solution the condition created.

Referring to Fig. 4 and Fig. 6, it is to obtain t that B point and C point are found the solution essence ₁, t ₂And G ₁Use temporary variable t ₁', t ₂' and G ₁' replacement t ₁, t ₂, G ₁, B ' and C ' replace B and C, because f _AB(t)=f _CD(t)=G ₁', then have

${{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;}=\frac{K_{\mathrm{CD}}\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}+b_{\mathrm{CD}}}{K_{\mathrm{AB}}}$

G ₁′＝K _CD×t ₂′+b _CD

Because with K _AB, K _CDAnd b _CDFind the solution out, as long as therefore calculate t ₂' can solve t ₁' and G ₁'.Suppose t by AB ' C ' ₂' constituted one trapezoidal, its trapezoidal area is S _F1Can be expressed as:

${\mathrm{<figure-callout\; id="1"\; label="S\; f"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">S</figure-callout>}}_f=\frac{(2\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}-{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^{\&prime;})\&times;{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}^{\&prime;}}{2}=\frac{K_{\mathrm{CD}}\&times;(2\&times;K_{\mathrm{AB}}-K_{\mathrm{CD}})\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;2}+2\&times;K_{\mathrm{AB}}\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}+{{\mathrm{<figure-callout\; id="2"\; label="b\; CD"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">b</figure-callout>}}_{\mathrm{CD}}}^2}{2\&times;K_{\mathrm{AB}}}$

The area of supposing A in the identical time period (t) is S _A1, can be expressed as

$S_{a1}={\&Integral;}_0^{{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}}A\left(t\right)\mathrm{dt}$

According to the equivalence principle that the embodiment of the invention is pointed out, promptly the area of A (t) and f (t) equates in the identical time period, that is to say that the area at the two equates then can be expressed as under the condition:

S _a1＝S _f1

Further can be expressed as:

${\&Integral;}_0^{{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}}A\left(t\right)\mathrm{dt}=\frac{K_{\mathrm{CD}}\&times;(2\&times;K_{\mathrm{AB}}-K_{\mathrm{CD}})\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;2}+2\&times;K_{\mathrm{AB}}\&times;{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}^{\&prime;}+{{\mathrm{<figure-callout\; id="2"\; label="b\; CD"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">b</figure-callout>}}_{\mathrm{CD}}}^2}{2\&times;K_{\mathrm{AB}}}$

Because

Be a transcendental equation, can not directly calculate t ₂', its method for solving need be by constantly adjusting t ₂' t when iterative computation finds area to equate ₂', this moment t ₂' be and treat evaluation t ₂, its Rule of judgment can be represented by the formula: t ₂=t ₂' | _DS=0, wherein, dS=S _A1-S _F1

To calculate the parametric t that constitutes BC like this ₁t ₂G ₁

Referring to Fig. 4 and Fig. 7, it is to solve t that D point and E point are found the solution essence ₃, t ₄And G ₂For A (t), because the above-mentioned t that solved ₃And t ₅, suppose at segment [t ₃, t ₅], the area of A (t) is S _A2, then can be represented by the formula:

$S_{a2}={\&Integral;}_{t_2}^{t_5}A\left(t\right)\mathrm{dt}$

For f (t), at segment [t ₃, t ₅] in, be by polygon t ₂CDEt ₅The area that constitutes can be seen as by t ₂CDt ₃Trapezoidal, t ₃DEt ₄Rectangle and t ₄Et ₅Triangle is formed, its area S _F2Can be expressed as:

${\mathrm{<figure-callout\; id="2"\; label="S\; f"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">S</figure-callout>}}_f=\frac{({\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1+G_2)\&times;(t_3-t_2)}{2}+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_4-t_3)+\frac{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_5-t_4)}{2}$

According to the equivalence principle that the embodiment of the invention proposes, promptly the area of A (t) and f (t) equates in the identical time period, then can be expressed as:

S _a2＝S _f2

${\&Integral;}_{t_2}^{t_5}A\left(t\right)\mathrm{dt}=\frac{({\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1+G_2)\&times;(t_3-t_2)}{2}+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_4-t_3)+\frac{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_5-t_4)}{2}$

Simultaneously can obtain following system of equations

$\left\{\begin{array}{c}{\&Integral;}_{t_2}^{t_5}A\left(t\right)\mathrm{dt}=\frac{({\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1+G_2)\&times;(t_3-t_2)}{2}+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_4-t_3)+\frac{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\&times;(t_5-t_4)}{2}\\ {\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=K_{\mathrm{CD}}{\&times;t}_3+{\mathrm{<figure-callout\; id="2"\; label="b\; CD\; G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">b</figure-callout>}}_{\mathrm{CD}}& \\ G_{}{}_2=K_{\mathrm{EF}}\&times;t_4+b_{\mathrm{EF}}\end{array}\right.$

Wherein, t ₅, G ₁, K _CD, K _EF, b _CD, b _EFWith

Be a constant, in three generations, asked parameter G ₂, t ₃, t ₄With three independent equations be to solve an equation, it resolves the result and is:

${\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=\frac{-{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">H</figure-callout>}}_2+\sqrt{{{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">H</figure-callout>}}_2}^2-4{\&times;\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1\&times;H_3}}{2{\&times;\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1};$ $t_3=\frac{G_2-b_{\mathrm{CD}}}{K_{\mathrm{CD}}};$ $t_4=\frac{G_2-b_{\mathrm{EF}}}{K_{\mathrm{EF}}};$ Wherein, ${\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">H</figure-callout>}}_1=\frac{1}{K_{\mathrm{EF}}}-\frac{1}{K_{\mathrm{CD}}};$

${\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">H</figure-callout>}}_2=\frac{G_1-b_{\mathrm{CD}}}{K_{\mathrm{CD}}}-\frac{b_{\mathrm{EF}}}{K_{\mathrm{EF}}}+t_5-{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000062765050000032.png"\; state="\{\{state\}\}">t</figure-callout>}}_2;$ With $H_3={\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1\&times;t_2-\frac{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000062765050000012.png,HDA0000062765050000022.png"\; state="\{\{state\}\}">G</figure-callout>}}_1\&times;b_{\mathrm{CD}}}{K_{\mathrm{CD}}}-2\&times;S_{a2}.$

So far, the embodiment of the invention can reflect A (t) feature by above step and the f (t) of equivalence on momentum in the ABCDE characteristic parameter of ordering find the solution and finish.

Referring to Fig. 8, with an experiment embodiment that how is found the solution double-trapezoidal wave by original crash data text is described below, see for details hereinafter and describe:

Referring to Fig. 9, it is the data file of relevant vehicle body acceleration in the vehicle impact testing, constitute by explanation and data two parts content, pointed out the essential information of data in the explanation, be included in channel number in the data acquisition system (DAS), dimensional unit that data are used is 10kHz as the sample frequency of g, data, actual collision speed is that 64.3km/h and file data amount are 3501.In sequence data, use CSV between the time of every group of data and the acceleration ,-50ms is as the starting point of data, and end point is 300ms, and the time interval is 0.1ms.The time null representation is the time of contact of collision, i.e. Peng Zhuan start time.Referring to Figure 10, this data file of serving as reasons imports to the acceleration time history curve that A (t) back produces.

To the foundation embodiment of the invention provide to vehicle body acceleration crest feature calculation method, after the data file of vehicle body acceleration handled, on this acceleration waveform, calculate corresponding wave crest point and trough point respectively, referring to Figure 11, shown [0,200] the corresponding respectively coordinate points of the Wave crest and wave trough in the time section is used P _iThe expression peak point, V _iExpression peak valley point, wherein i is a sequence number, has 14 groups of Wave crest and wave troughs.

Referring to Figure 12, Figure 13, Figure 14, Figure 15 and Figure 16, A (t) is carried out integration, formation speed Speed (t), pointwise compares Speed (t) and actual collision speed Velocity then, and finding the pairing time of speed point that equates first is 142.8ms.Finished finding the solution that A point and B order thus, i.e. A (0,0) and F (142.8,0).

Constitute f _AB(t) be A (0,0) and first wave crest point P ₁(6.1,8.19); After this sequence number i=4 of the maximum valley peak value of Chu Xianing that is to say to constitute f _CD(t) point is V ₄And P ₅, corresponding coordinate figure is: V ₄(41.8,4.66) P ₅(59.3,19.60), the maximum peak valley appears at sequence number i=11 so, and corresponding point is V ₁₁And P ₁₁, corresponding coordinate figure is V ₁₁(141.2,2.68) and P ₁₁(108.3,24.12).

Constraint function	Related sequence number	The associated coordinates value
			f AB(t)	1	A(0，0)；P 1(6.1，8.19)
f CD(t)	4	V 4(41.8，4.66)；P 5(59.3，19.60)
			f EF(t)	11	P 11(108.3，24.12)；F(142.8，0)

Can calculate the slope value of line segment function and cut the square value:

K _AB＝1.342623；b _AB＝0.000000；

K _CD＝0.853714；b _CD＝-31.025257；

K _EF＝-0.699130；b _EF＝99.835826。

Unique point B is subjected to the line segment function f _AB(t) restriction, it is at f all the time _AB(t) on the track; In like manner, unique point C is subjected to the line segment function f _CD(t) restriction, it is at f all the time _CD(t) on the track.G as can be seen from Figure ₁, t ₁And t ₂Variation range is separately all arranged, G ₁Variation range be to form by maximum crest value in this interval and minimum trough value, also formed t thus ₁And t ₂Variation range.An intermediate variable be need set for the ease of iterative computation and continuous iterative computation, i.e. t finished ₁Corresponding intermediate variable is t ₁', t ₂Corresponding intermediate variable is t ₂', G ₁Corresponding intermediate variable is G ₁', and agreement G ₁Maximal value is by f _CD(t) t that obtains ₂' the beginning iterative computation, calculate G ₁=7.23, t ₁=5.4 and t ₂=44.8.

Unique point D is subjected to the line segment function f _CD(t) restriction, it is at f all the time _CD(t) on the track; Unique point E is subjected to the line segment function f _EF(t) restriction, it is at f all the time _{EF (}(t) on the track.Because t ₂Found the solution and finished, that is to say, for A (t), at interval [t ₂, t ₅] in its area value fix, after integral and calculating, obtain S _A2=1515.808, G as can be seen from Figure ₂=18.88, t ₃=18.9 and t ₄=115.9.

Referring to Figure 17, so far, the characteristic parameter that will constitute f (t) is all found the solution and is finished.

In sum, the embodiment of the invention provides a kind of car crass waveform character parameter extraction and trapezoidal wave construction method, the present invention has formed a crash acceleration waveform complicated and changeable has been simplified the mathematical model of equivalence for the double-trapezoidal wave statement, its using value is a challenge is oversimplified, with 10 ³The crash acceleration series data of the order of magnitude is reduced to 6 series datas; Its construction value is to use principle of conservation of momentum and similarity principle has solved the equivalent relation of double-trapezoidal wave on action time and energy, this double-trapezoidal wave is equivalent with actual waveform on macroscopical waveform, the method of Xing Chenging has repeatability on engineering thus, enlarged popularizing and practical application of double-trapezoidal wave parameter, can realize with concrete method on computers.

It will be appreciated by those skilled in the art that accompanying drawing is the synoptic diagram of a preferred embodiment, the invention described above embodiment sequence number is not represented the quality of embodiment just to description.

The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (1)

1. car crass waveform character parameter extraction and trapezoidal wave construction method is characterized in that, said method comprising the steps of:

(1) from the data acquisition system (DAS) of vehicle impact testing, gathers the vehicle body acceleration information data, obtain acceleration A (t);

(2) discern wave crest point, trough point in the described acceleration A (t);

(3), make up wave function f (t) with double-trapezoidal wave feature according to similarity principle and principle of conservation of momentum according to described acceleration A (t); Wherein,

The horizontal ordinate of the wave function f (t) of described double-trapezoidal wave feature is the time variable axle, ordinate is described acceleration A (t) variable axle, the wave function f (t) of described double-trapezoidal wave feature is made of A, B, C, D, E and 6 data points of F, and corresponding coordinate figure is respectively (t ₀, G ₀), (t ₁, G ₁), (t ₂, G ₁), (t ₃, G ₂), (t ₄, G ₃) and (t ₅, G ₀); Wherein, A (t ₀, G ₀) be the double-trapezoidal wave starting point, t ₀Be the collision initial moment of contact, and t ₀=0; F (t ₅, G ₀) be the double-trapezoidal wave terminating point, t ₅For colliding the finish time; G ₀Actual value be 0; The coordinate figure of described A, B, C, D, E and F6 data point formation is respectively (0,0), (t ₁, G ₁), (t ₂, G ₁), (t ₃, G ₂), (t ₄, G ₃) and (t ₅, 0); Or,

The wave function f (t) of described double-trapezoidal wave feature is made up of AB, BC, CD, DE and five line segments of EF, and line segment BC and DE correspond respectively to G for being parallel to described time variable axle ₁And G ₂, line segment AB, CD and EF are the stringcourse of double-trapezoidal wave, respectively corresponding line segment function f _AB(t), f _CD(t) and f _EF(t); Wherein,

f _AB(t)＝K _AB×t；

f _CD(t)＝K _CD×t+b _CD；

f _EF(t)＝K _EF×t+b _E；；

K _AB, K _CDAnd K _EFBe described line segment function f _AB(t), f _CD(t) and f _EF(t) slope, b _CDAnd b _EFBe described line segment function f _CD(t) and f _EF(t) intercept;

Wherein, wave crest point, the trough point in the described acceleration A of identification (t) is specially described in the step (2):

The mean value of described wave crest point both sides at certain time intervals is all less than crest value; The mean value of described trough point both sides at certain time intervals is all greater than the trough value; (t) carries out the search of described wave crest point and described trough point to described acceleration A, and the number of times of search is N, and the value of N is a positive integer; Definition maximum valley peak A PVmax and maximum peak valley AVPmax, the search sequence of paddy peak value number are i, and the search sequence of peak-to-valley value number is j;

Wherein, according to described acceleration A (t), make up wave function f (t) according to similarity principle and principle of conservation of momentum and be specially described in the step (3) with double-trapezoidal wave feature:

According to first wave crest point P that occurs in the described acceleration A (t) ₁And the line segment between the described starting point A makes up described line segment function f _AB(t);

At described first wave crest point P ₁The peak valley point and the peak point P of the maximum valley peak value correspondence of Chu Xianing afterwards _I+1Make up described line segment function f _CD(t);

According to

Obtain the value of i;

Peak point P according to maximum peak valley correspondence _jMake up described line segment function f with the F point _{EF (t)}

According to

Obtain the value of j;

Definition temporary variable t ₁', t ₂' and G ₁' replacement t ₁, t ₂, G ₁B ' and C ' replace B and C, because f _AB(t)=f _CD(t)=G ₁', then have

${t_1}^{\&prime;}=\frac{K_{\mathrm{CD}}\&times;{t_2}^{\&prime;}+b_{\mathrm{CD}}}{K_{\mathrm{AB}}}$

G ₁′＝K _CD×t ₂′+b _CD

By AB ' C ' t ₂' constituted one trapezoidal, its trapezoidal area

$S_{f1}=\frac{(2\&times;{t_2}^{\&prime;}-{t_1}^{\&prime;})\&times;{G_1}^{\&prime;}}{2}=\frac{K_{\mathrm{CD}}\&times;(2\&times;K_{\mathrm{AB}}-K_{\mathrm{CD}})\&times;{t_2}^{\&prime;2}+2\&times;K_{\mathrm{AB}}\&times;{t_2}^{\&prime;}+{b_{\mathrm{CD}}}^2}{2\&times;K_{\mathrm{AB}}};$

The area of A in the identical time period (t) is

Area according to A (t) in the identical time period and f (t) is equal, then S _A1=S _F1

${\&Integral;}_0^{{t_2}^{\&prime;}}A\left(t\right)\mathrm{dt}=\frac{K_{\mathrm{CD}}\&times;(2\&times;K_{\mathrm{AB}}-K_{\mathrm{CD}})\&times;{t_2}^{\&prime;2}+2\&times;K_{\mathrm{AB}}\&times;{t_2}^{\&prime;}+{b_{\mathrm{CD}}}^2}{2\&times;K_{\mathrm{AB}}}$

By continuous adjustment t ₂' t when iterative computation finds area to equate ₂', its Rule of judgment is t ₂=t ₂' | _DS=0Wherein, dS=S _A1-S _F1

At segment [t ₃, t ₅], the area of A (t) is S _A2,

Polygon t ₂CDEt ₅The area that constitutes is by t ₂CDt ₃Trapezoidal, t ₃DEt ₄Rectangle and t ₄Et ₅Triangle is formed,

$S_{f2}=\frac{(G_1+G_2)\&times;(t_3-t_2)}{2}+G_2\&times;(t_4-t_3)+\frac{G_2\&times;(t_5-t_4)}{2}$

Area according to A (t) in the identical time period and f (t) is equal, then S _A2=S _F2

$\left\{\begin{array}{c}{\&Integral;}_{t_2}^{t_5}A\left(t\right)\mathrm{dt}=\frac{(G_1+G_2)\&times;(t_3-t_2)}{2}+G_2\&times;(t_4-t_3)+\frac{G_2\&times;(t_5-t_4)}{2}\\ G_2=K_{\mathrm{CD}}{\&times;t}_3+b_{\mathrm{CD}}\\ G_2=K_{\mathrm{EF}}\&times;t_4+b_{\mathrm{EF}}\end{array}\right.$

$G_2=\frac{-H_2+\sqrt{{H_2}^2-4{\&times;H}_1\&times;H_3}}{2{\&times;H}_1};$ $t_3=\frac{G_2-b_{\mathrm{CD}}}{K_{\mathrm{CD}}};$ $t_4=\frac{G_2-b_{\mathrm{EF}}}{K_{\mathrm{EF}}};$

Wherein, $H_1=\frac{1}{K_{\mathrm{EF}}}-\frac{1}{K_{\mathrm{CD}}};$ $H_2=\frac{G_1-b_{\mathrm{CD}}}{K_{\mathrm{CD}}}-\frac{b_{\mathrm{EF}}}{K_{\mathrm{EF}}}+t_5-t_2;$ $H_3=G_1\&times;t_2-\frac{G_1\&times;b_{\mathrm{CD}}}{K_{\mathrm{CD}}}-2\&times;S_{a2}.$

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